CODEWITHSUNDEEP
python
Iowa
Iowa

Reputation: 2491

Python: Passing value of a string variable as argument in Popen

What is the proper way to pass values of string variables to Popen function in Python? I tried the below piece of code

var1 = 'hello'
var2 = 'universe'
p=Popen('/usr/bin/python /apps/sample.py ' + '"' + str(eval('var1')) + ' ' + '"' + str(eval('var2')), shell=True)

and in sample.py, below is the code

print sys.argv[1]
print '\n'
print sys.argv[2]

but it prints the below output

hello universe
none

so its considering both var1 and var2 as one argument. Is this the right approach of passing values of string variables as arguments?

Upvotes: 0

Views: 2820

Answers (2)

Nilesh
Nilesh

Reputation: 2555

var1 = 'hello'
var2 = 'universe'
p=Popen("/usr/bin/python /apps/sample.py %s %s"%(str(eval('var1')), str(eval('var2'))), shell=True)

Passing format specifier is nice way to do it.

Upvotes: 0

warvariuc
warvariuc

Reputation: 59674

This should work:

p = Popen('/usr/bin/python /apps/sample.py {} {}'.format(var1, var2), shell=True)

Learn about string formatting .

Second, passing arguments to scripts has its quirks: http://docs.python.org/2/library/subprocess.html#subprocess.Popen

This works for me:

test.py:

#!/usr/bin/env python

import sys

print sys.argv[1]
print '\n'
print sys.argv[2]

Then:

chmod +x test.py

Then:

Python 2.7.4 (default, Jul  5 2013, 08:21:57) 
>>> from subprocess import Popen
>>> p = Popen('./test.py {} {}'.format('hello', 'universe'), shell=True)
>>> hello


universe

Upvotes: 1

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